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Dental Materials Research Supporting Your Practice

Biochemical Stability and Interactions of Dental Resin Composites and Adhesives with Host and Bacteria in the Oral Cavity: A Review

I had the pleasure to host Dr. Yoav Finer for a conversation on the recent article he published in the Journal of the Canadian Dental Association. The article is important due to continuous debate around the use of amalgam vs. the use of newer composite materials. Research is dearly needed to gauge the efficiency, durability, and long-term stability of the new materials compared to the time-tested and proven amalgam. 

Dr. Finer is the George Zarb/Nobel Chair in Prosthodontics at the faculty of dentistry, University of Toronto, and is cross-appointed to the Institute of Biomaterials and Biomedical Engineering, University of Toronto.

As usual, we hope that you enjoy the conversation and find it beneficial. We would love to hear from you, please share your thoughts, questions and suggestions through oasisdiscussions@cda-adc.ca

Until next time!

Chiraz Guessaier
CDA Oasis Manager


Download the JCDA article (PDF): Biochemical Stability and Interactions of Dental Resin Composites and Adhesives with Host and Bacteria in the Oral Cavity: A Review


  • The use of resin composites and adhesives in dental restorations is ubiquitous. However, the longevity of resin composites is less than that of comparable restorative materials, mainly because of higher fracture rates and greater prevalence of secondary caries.
  • Dental resin composites and adhesives contain ester links, which are vulnerable to biochemical hydrolysis by esterase activity from human saliva and bacteria.
  • In this article, the authors review biodegradation processes that occur in the oral cavity and their contribution to the premature failure of resin composites. Biodegradation causes deterioration of resin composite bulk and the composite–tooth interface and releases by-products, such as methacrylic acid, triethylene glycol and bishydroxy-propoxy-phenyl-propane. These by-products have been shown to affect cariogenic bacterial growth and virulence.
  • A compromised restoration–tooth interface allows saliva and oral bacteria to infiltrate the spaces between the tooth and the composite, exacerbating the effects of biodegradation, undermining the restoration and leading to recurrent caries, hypersensitivity and pulpal inflammation.
  • It is important to consider the biochemical stability of these materials to advance their chemistry beyond the current formulations and conceive more biochemically stable and better-performing dental resin composites and adhesives.

Full Conversation (11.53″)





  1. ken stones February 13, 2018

    Very good to hear some researched comments on the shortcomings and failures of composite as a material!! I believe this material is very often used inappropriately causing “iatrogenic” problems for many patients. As Dr Finer points out, the breakdown of the material and high secondary caries rates “results in repeated replacements ….and we all know these replacements cannot be done indefinitely”.
    If we are to replace using amalgam to restore teeth, surely it should not be with the inferior composite material!
    Ken Stones

    1. Cliff Leachman February 15, 2018

      Man this is like the second article posted praising amalgam, too bad it’s too late for the younger dentists who are full on Bondi kings.
      Some days I feel like they’re going to come take me away for using amalgam.
      But not from my cold, dead hands…..

      1. JCDA Oasis February 15, 2018

        Dr. Leachman,

        Thank you for leaving your comment, it’s always a pleasure to read your notes. Check out Dr. Belzycki’s post that will go live few hours from now. It may be the third article 🙂

        Take care,
        CDA Oasis Team

  2. noah weiszner February 14, 2018

    Seems to me that it’s the open contact that produces a food trap that is more of the cause of recurrent caries.
    However, in my experience, an amalgam, long-term, is a better material than a composite

  3. Dr. Larry Hoffman February 21, 2018

    I agree that composite restorations are plaque magnets, but both restorations in 45 and 46 are poorly done, the integrity of the tooth shape has not been kept. As my hygienist said, the problem with the recurrent decay is “pilot error” not material failure. I would say that all materials would fail, if the contact was like this.

    1. Jamie February 21, 2018

      I agree Larry…sure all restorations would fail. But which is more user friendly? Which material has the higher chance of success in average hands? Most of us fall in the middle of the bell curve and are average…many are well below average…from a pure risk assessment philosophy, which material gives the “best” chance at full spectrum successes? It has little to do with which material is better…we all know they all have different properties that give them pros and cons. I would like there to be more of a consensus of thought about these pros and cons from a scientific point of view, rather than emotional. The more tools in one’s toolbox, the more options for success…we are not so different from builders, contractors or mechanics…one material is rarely a cure-all. It’s good and prudent to use all types of materials based on what’s best for the patient, rather than what material makes you better able to “market” your practice and help you stand out from your neighbor.

  4. Dr. Garnet Packota February 21, 2018

    Some of our patients, and others, get concerned about the toxicity of mercury in amalgam. Are they aware that composite materials also contain components that are also potentially toxic?

    In a similar vein to Dr. Leachman’s comments, for many reasons I hope I’ll be cold and dead before my posterior amalgams are replaced by composite.

  5. Dr. Terry James February 21, 2018

    Thank you for sending this opinion on dental amalgam vs. bonded resin. I am a relatively new dentist and I still use amalgam on a regular basis, so before we say all new dentists use exclusively composite materials, I would disagree. There are simply times and places where amalgam will outperform resin hands down and we need to use our clinical judgement to do what’s best for our patients. If we aren’t isolating our field from moisture and closing contacts, composite resins are vulnerable to say the least. I will routinely explain to patients why I think another material will work better in certain circumstances and it can be very frustrating when patients choose to avoid ‘toxic mercury’ based on questionable science and public opinion. I truly believe informed consent is the process of allowing the patient to understand and choose their treatment, and it is not simply your signature on a piece of paper. I’ve had a number of situations where patients choose a Class V amalgam on a mandibular molar when they understand that it is impossible to isolate and I’m happy to provide that option for my patients. Placing a resin in a situation where moisture has contaminated the preparation and not informing the patient is arguably malpractice, no different than a perforation in endodontics or iatrogenic trauma during surgery. Is it because ‘it’s just a filling’ make it ok?

    Welcome any other opinion or disagreement on this topic, just my two cents.

  6. Chris Bryant, Sooke BC February 21, 2018

    A great summary of why we need to be as diligent as all can be when trying to do our best with adhesive dentistry. Cariogenic tendencies of restorative material components has been a poster/table clinic matter at IADR meetings for too long…….this is a wise time for this to be distributed to general dentists.


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